1. Field of the Invention
The present invention relates to a method of engine operation to provide a real time engine diagnostic to detect malfunctions covered by hardware failure that may cause the engine or its components to be damaged, or their performance to be degraded, or the engine exhaust emissions to be non-compliant.
The present invention is further related to a method of engine operation to provide a real time engine diagnostic to detect EGR, turbocharger or compressor malfunctions and to prevent such malfunctions from damaging the engine.
2. Description of the Related Art
Kreso, U.S. Pat. No. 6,588,210 discloses the system and method for measuring the flow rate of recirculated exhaust gas in the compression ignition engine including a plurality of engine sensors having outputs indicative of current engine condition and a turbocharger. The system includes an exhaust gas recirculation valve mounted in the exhaust pipe upstream of the turbocharger for diverting a selectable portion of the exhaust gas for recirculation in combination with the charge air, one or more sensors for sensing current conditions of the recirculated exhaust gas, including temperature and pressure, one or more sensors for sensing current conditions of the intake air, and control logic for determining the flow rate of the recirculated exhaust gas as a function of the sensed conditions. In one embodiment, the system includes an obstruction in the flow path of the recirculated exhaust gas and a different pressure sensor for determining the pressure differential between a point upstream of the obstruction and a point downstream as the obstruction and control logic for determining the flow rate of the recirculated gas as a function of the current intake manifold pressure, the recirculated exhaust gas temperature, and the differential pressure drop across the obstruction.
In the differential pressure embodiment, the flow rate of the recirculated gas is determined from the voltage input from the differential pressure sensor and from the sensed recirculated exhaust gas temperature, according to the formula EGR flow rate (KG/MIN) equals EGR gas density/density collection) a*b* (differential pressure drop, kPa)c where the density correction a, b, and C are each calibratable constants for a particular orifice design.